Naphthylene derivatives

ABSTRACT

Novel naphthylcyclopentanone derivatives are described which are useful as intermediates for and as pharmacological agents. Representative compounds are 3-(6&#39;&#39;-methoxy-2&#39;&#39;-naphthyl)-2methylcyclopentanone-2-acetic acid, the cyclopentanol analog, their methyl and other alkyl esters, acid addition salts thereof, their racemic and optically active forms.

United States Patent Brain et al.

NAPHTHYLENE DERIVATIVES Inventors: Edward George Brain, Leigh; John Christopher Hanson, Newdigate; Minoo Dossabhoy Mehta, Wimbledon, all of England Assignee: Beecham Group Limited, Brentford,

Middlesex, England Filed: July 1, 1971 Appl. No.: 159,037

Related U.S. Application Data Continuation of Ser. No. 639,023, May 17, 1967, abandoned.

U.S. Cl 260/473 F, 260/311, 260/488 CD, 260/520, 260/586 R, 260/613 D, 260/619 F, 260/999 Int. Cl. C07c 69/88 UNITED STATES PATENTS 3,649,678 3/1972 Fusco et al. 260/520 Primary Examiner-Lorraine A. Weinberger Assistant ExaminerL. A. Thaxton [57] ABSTRACT Novel naphthylcyclopentanone derivatives are described which are useful as intermediates for and as pharmacological agents. Representative compounds are 3-(6-methoxy-2'-naphthyl)-2-methylcyclopentanone-2-acetic acid, the cyclopentanol analog, their methyl and other alkyl esters, acid addition salts thereof, their racemic and optically active forms.

3 Claims, No Drawings 1 NAPHTHYLENE DERIVATIVES in which R is an alkyl group having 1 6 carbon atoms; R, is a hydrogen atom or an alkyl or dialkylaminoalkyl group; R is a carboxy, carboxyalkyl, earboxydialkylaminoalkyl, hydroxymethyl, methoxymethyl or acyloxymethyl group; Z is CO which may be thioketalised, CHOH, CHOAc, CHOCH C(OH)C:CH or CzNOH,

Ac being an acyl group; Y is CH CO, C:NOl-l,-

CsCHOH, CzCHSR or C:CHNR R in which R is an alkyl group and R and R are the same or different to introduce the angular alkyl group R, wherein X is a protecting group, and then before or after removal of group X, if desired replacing substituents R, and/or R in known manner, and if desired, thioketalising the lketo group to other groups Z in known manner and after removal of group X if desired introducing the other groups Y, and if desired forming acid addition salts of those compounds having basic groups.

Preferably the alkylation is effected by using an alkyl halide in presence of an alkali metal alkoxide, especially potassium t-butoxide.

Preferably in compound (ll) during the alkylation R is a carboxyalkyl groupand the protecting group X is benzylidene, furfurylidene, CHSR or CHNR R especially the CHN(CH )(C H group, and this may be converted to a compound (I) in which Y is a CH group by vigorous hydrolysis, for example with aqueous sodium hydroxide in a higher boiling alcohol such as methoxyethanol. During the hydrolysis group R when a carboxyalkyl group may be converted to a carboxy 5 group, which group may be subsequently esterified, for

example by using a diazoalkane.

Products having other substituents may be prepared in known way, for example, when R is an alkyl group, dealkylation gives compounds in which R is a hydrogen atom and these compounds may be reacted with an alkyl or dialkylaminoalkyl halide.

Similarly compounds in which Z is a CO group may be treated by known methods to introduce other substituents. I

The starting compounds of formula (ll) may be prepared by treating a compound of the formula:

(III) in which R and R are alkyl groups, with an alkyl formate and alkali metal alkoxide to give a compound of the formula: I

wherein R is a hydrogen atom or an alkyl group, and

then introducing group X in the 5-position of the cyclopentanone ring and when R is a hydrogen atom, esterifying the COOH group to form a carboxyalkyl group. Suitably, the compound (1V) is reacted with a s-amine R R NH (wherein at least one of R and R is aryl) to form the protecting group CHNR R Reactions used to change substituents in compounds 7 (1) include:

a. dealkylation with pyridine hydrochloride to give compounds in which R, is a hydrogen atom, followed by alkylation or dialkylaminoalkylation, b. reduction of group Z C0 to give Z CHOH, 0. reduction of R COOH to R CH OH, d. reaction of group Z CO with a Grignard reagent, followed by hydrolysis.

The following Examples 3 to 17 illustrate the inventlon.

EXAMPLE 1 stirred, ice-cooled suspension of methanol-free sodium methoxide (21.7 g.) in dry methyl formate (24 g.) and dry benzene (250 ml.) and then allowed to reach 20C with stirring. After 16 hours at this temperature the suspension was cooled and shaken with ice cold 5N. sulphuric acid (100 ml.). The benzene layer was washed with water 100 ml. extracted with percent sodium hydroxide (80 ml.) and then with water (100 ml.). The aqueous alkaline extracts were acidified with 5N. hydrochloric acid (50 ml.), and the crude 5-formyl-3-(6'- methoxy-2'-naphthyl)cyclopentanone-Z-acetic acid was filtered off and dried to a fine pale fawn powder (20.2 g.), U.V. (EtOH) )tmax. 23311., 273/ (-72,000,

. 17,000, (NaOH/EtOH) Amax. 233,12 312/ (-72,000,

26,000). This product was refluxed in benzene (150 ml.) with N-methylaniline (17 ml.) for 0.5 hr. with continuous removal of the water formed by means of a Dean and Stark head. The reaction liquor was cooled and the crystals of 5-N-methylanilinoformyl-3(6- methoxy-2'-naphthy1)cyclopentanone-Z-acetic acid (16.6 g; 58 percent) were filtered off and washed with benzene (10 ml.), m.p. 193- 194C; U.V. (in EtOH) )tmax. 231 1., 339 u; (-99,000,33,000)(Found: C, 75.2; H 5.93; N, 3.13; C H NO, requires C, 75.18; H, 6.02; N, 3.37 percent). In some experiments methyl 5- formyl-3-(6l-methoxy-2'-naphthyl)-cyclopentanone- 2-acetate was obtained, which on reaction with N- methyl-aniline gave the ester described in Example 2.

EXAMPLE 2 A solution of the acid of Example 1 (16.6 g) in tetrahydrofuran (300 ml.) was treated with diazomethane (from nitrosomethylurea, 8 g) in ether (400 ml.) and stirred for 20 hours. After removal of the solvent,.the residue was recrystallised from methanol (400 ml.) to give methyl S-N-methylanilinoformyl-3-(6-methoxy- 2'-naphthyl)cyclopentanone-Z-acetate (15.2 g. 89 percent), m.p. 138 140C (Found: C, 75.4; H, 6.37; N, 3.18; C H NO requires C, 75.51; H, 6.33; N, 3.26 percent).

EXAMPLE 3 A solution of the ester of Example 2 (125 g) in hot dry tetrahydrofuran (450 ml.) was cooled to 20C and added simultaneously with methyl iodide (120 g., excess) to a solution, obtained by dissolving potassium (24 g.) in dry t-butanol (350 ml.) and dry tetrahydrofuran (350 ml.) at l0C 0C under nitrogen. The reaction mixture was kept at 0C for 1 hr. and allowed to reach room temperature during a further'l hour. The solvents were removed in vacuo at approx. 20C. Ether (500 ml.), water (200 ml.) and 1N sodium bicarbonate solution (500 ml.) were added, shaken thoroughly then filtered, giving 117 g. of solid. The ether filtrate was washed with water and evaporated, then the residue was crystallised from methanol.

The combined solids were Soxhlet-extracted with methanol (500 ml.). On cooling, the methanolic extract deposited methyl 5-methylanilinoformyl-3-(6- methoxy-2-naphthyl)-2-methyl-cyclopentanone- 2-acetate (96 g., 79 percent), m.p. 164 165C. (Found: C, 75.6; H, 6.79; N, 3.08; C2gH29NO4 requires: C, 75.85; H, 6.59; N, 3.16 percent).

EXAMPLE 4 A solution of methyl 5-methy1anilinoformyl-3-(6- methoxy-2-naphthyl)-2-methylcyclopentanone- 2-acetate (4.77 g) in methoxyethanol (30 ml.) was refluxed with 40 percent aqueous sodium hydroxide solution (20 ml.) for 3 hours. The mixture was cooled, diluted with water ml.), acidified with 5N. hydrochloric acid (40 ml.), extracted with ether (2 X 100 m1.) and the ether layer was washed with water (2 X 30 ml.). The ether was distilled off to leave a crystalline residue (3.42 g), which was recrystallised from benzene (100 ml.) to give 3-(6-methoxy-2'-naphthyl)-2- methylcyclopentanone-2-acetic acid (2.74 g., 81 percent), m.p. 151 153C (Found: C, 73.2; H, 6.76; C H O requires C, 73.06; H, 6.45).

EXAMPLE 5 A solution of 3-(6'-methoxy-2-naphthyl)-2- methylcyclopentanone-2-acetic acid (2 g.) in tetrahydrofuran (50 ml.) was. treated with diazomethane (from nitrosomethylurea, 2 g. )in ether (200 ml.) for 2 hours. After removal of the solvent, the residue was distilled in vacuo (b.p. ca. /10 mm.) to give methyl EXAMPLE 6 3(6'-Methoxy-2'-naphthyl)-2-methylcyclopentanone-2-acetic acid (6g.) was dissolved in 5 percent sodium hydroxide solution (250 ml.), sodium borohydride (3 g.) was added and the mixture was stirred at room temperature for 18 hours. Acetic acid (30 ml.) was added dropwise to decompose the complex and excess borohydride, and then the solution was strongly acidified with concentrated hydrochloric acid. It was extracted with ethyl acetate (3 X 75 ml.) and the combined organic extracts were washed with saturated sodium bicarbonate solution (3 X 75 ml.), then with brine (50 ml.), dried (Na SO and evaporated. The residue was crystallised from ethyl acetate to give 3-(6'- methoxy-2-naphthyl)-2-methylcyelopentanol-Z-acetic acid cis-lactone (3.3g, 58 percent), m.p. 159- 160C (Found: C, 77.19; H, 6.91, C H O requires C, 77.00; H, 6.80 percent); i.r. (5 percent solution in CHCI band at 1760 cm (lactone carbonyl). The n.m.r. showed a singlet at 8.551 (angular methyl/group) and a multiplet at 5.2 5.4T (proton adjacent to lactone ring).

The above-mentioned sodium bicarbonate extracts were acidified with dilute hydrochloric acid and extracted with ethyl acetate (3 X 30 ml.). The combined organic extracts were washed with brine (20 ml), dried (Na SO and evaporated. The residue was crystallised fron benzene to give 3-(6-methoxy-2-naphthyl)-2- methylcyclopentanol-Z-trans acetic acid (1g., 17 percent), m.p. 156 158C; i.r. (2 percent solution in CHCl bands at 1720 cm (acid carbonyl), 3660 cm and 3570 cm (carbonyl OH). The n.m.r. showed a singlet at 8.81r (angular methyl group) and a multiplet at 5.5 5.71- (proton adjacent to OH group).

EXAMPLE 7 Lithium aluminium hydride (0.45 g., 2 equivs) was stirred with dry ether ml.) for 0.5 hour, then a solution of 3-(6'-methoxy-2'-naphthy1)-2- methylcyclopentanol-2-acetic acid cis-lactone (3.5 g.)

in tetrahydrofuran 150 ml.) was added dropwise to the suspension. The resulting mixture was refluxed for 2 hours and cooled in ice. The complex was decomposed by the alternate additions of water and 20 percent sodium hydroxide solution until a granular solid resulted. The solution was decanted, dried (Na SO and evaporated to dryness. The residue was crystallised from ethyl acetate to give cis-2-(2-hydroxyethyl)-3 (6- methoxy-2'-naphthyl)-2-methylcyclopentanol (2.8g, 79 percent), m.p. 158 160C (Found C, 76.12; H, 8.31; C, H O requires C, 75.98; H, 8.00 percent), i.r. (5 percent solution in CHCl bands at 3600 cm and 3300cm- (OH groups). The n.m.r. showed a singlet at 8.907 (angular methyl group) and a multiplet at 6.08 6.227 (proton attached to cyclopentanol OH overlaid by methoxy] signal).

EXAMPLE 8 EXAMPLE 9 To 2-(2-Hydroxyethyl)-3-(6-methoxy-2- naphthyl)-2-methyl-cyclopentanol (0.3g) in dry dichloromethane (20 ml.) was added anhydrous aluminium chloride (ca. 0.5g) and the ice-cooled mixture was treated dropwise with dry solution of diazomethane in ether with stirring until the yellow colour persisted, then the mixture was stirred for a further 0.5 hour. It was washed with dilute hydrochloric acid (20 ml.), 10 percent sodium carbonate solution (20ml), water (20 ml.) and brine (20 ml.), dried (MgSO ),'and evaporated.

The product was chromatogrammed on two 40 X 20- cm. silica gel GF plates (1 mm. thickness) using 40 percent ethyl acetate in petrol (b.p. 60 80C) for developing. The main zone was eluted with ether, which was evaporated to give l-methoxy-2-(2- methoxyethyl)-3-(6-methoxy-2-naphthyl)-2-methylcyclopentane (0.256g., 29 percent). On crystallisation from petrol at low temperature the m.p. was 72 74C (Found: C, 76.70; H, 8.65; cg Hggog requires C, 76.78; H, 8.59 percent). N.m.r. showed singlets at 8.947 (angular methyl group), 6987, 6.647 (aliphatic methoxy groups) and 6.137 (aromatic methoxy group).

EXAMPLE 10 To an ice-cooled solution of 2-(2'-hydroxyethyl)- 3(6-methoxy-2-naphthyl)-2-methylcyclopentanol (0.5g) in pyridine (2.5 ml.) was added acetic anhydride (0.7g) and the mixture was allowed to stand at room temperature for 7 hours. It was poured into ice-cold dilute hydrochloric acid (25 -ml.), and extracted with ether (3 X 25 ml.). The organic extracts were washed with sodium bicarbonate solution (25 ml.) water (25 ml.) and brine (25 ml.), dried (MgSO and evaporated to leave 1-acetoxy-2-(2-acetoxyethy1)-3-(6-methoxy- 2'-naphthy1)-2-methy1cyclopentanone as an oil (0.63 g.

6 99 percent) (Found: C, 71.91; H, 7.50; C H O requires C, 71.86; H, 7.34 percent), i.r. (5 percent solution in CC1 band at 1740 cm (acetate carbonyl) and a-strong band at 1380 cm (acetate methyl.) The n.m.r. showed singlets at 8.86p (angular methyl), 8.127 and 7.917 (acetate methyls) and a multiplet at 4.9 5.157 (proton adjacent to cyclopentyl acetate group).

EXAMPLE 1 l 3-(6'-Methoxy-2'-naphthyl)-2-methylcyclopentanone-2-acetic acid (10.4 g) was heated with freshly distilled dry pyridine hydrochloride (24 g) at 180200C. for 2 hours, cooled and dissolved by shaking with N- hydrochloric acid (250 ml.) and ether (200 ml.) The ether layer was extracted with 1 N.aqueous sodium bicarbonate (2 X 50 ml) and water (2 X 50 ml.).

The sodium bicarbonate extract was acidified and extracted with ether, which on evaporation and crystallisation from ethyl acetate gave 3-(6'-hydroxy-2'- naphthyl)-2-methylcyclopentanone-2-acetic acid (7.1 g., 71 percent), m.p. 224225C (Found: C, 72.62; H, 6.07; C, H, O requires C, 72.47; H, 6.08 percent).

EXAMPLE 12 The acid from Example 11 (6.2 g) was treated with sodium borohydride (2.4 g) as described in Example 6. The products were dissolved in ethyl acetate and extracted with: (1) aqueous sodium bicarbonate to give 3-(6-hydroxy-2'-naphthyl)-Z-methylcyclopentanol-Z- trans-acetic acid (7 percent) on acidification, m.p. l69170C; (2) aqueous sodium hydroxide to give 3- (6-hydroxy-2-naphthyl)-2-methylcyclopentanol-2- acetic acid cis-lactone (70 percent), crystallised from ethanol-tetrahydrofuran, mp. 224C. The lactone was then reduced with lithium aluminium hydride as described in Example 7. The product was crystallised from chloroform, then ethyl acetate to give cis-2-(2- hydroxyethyl)-3-(6'-hydroxy-2-naphthyl)-2- methylcyclopentanol (50 percent), m.p. 182 185C.

EXAMPLE 1 3 Methyl 3-(6'-Methoxy-2'-naphthy1)-2- methylcyclopentanone-2-acetate (7.02 g.), ethanedithiol (7.ml.), dry ether (35 ml and boron trifluoride etherate (7 ml.) were thorouglh y mixed and allowed to stand for 24 hours at 20C.'5 percent Sodium hydroxide was added cautiously with cooling, and the ether solution was thoroughly washed-with 5 percent sodium hydroxide (3 X 50 ml.) and water (3 X 50 ml.). The ether solvent was evaporated and the residue crystallised from ethanol (150 ml.) to give methyl 3-(6- methoxy-2'-naphthyl)-2-methyl-cyc'lopentanone- 2-acetate ethanadethiol ketal (5.23 g., 60 percent), mp. 925C. (Found: C, 65.31; H, 6.47; S, 16.3 C I-1 0 8 requires C, 65.62; H, 6.51; S, 15.9 percent). I

The thioketal ester (2.01 g.) in dry tetrahydrofuran (20 ml.) was added to a suspension of lithium aluminium hydride (0.5 g) in dry ether (20 ml.) and dry tetrahydrofuran (20 m1.), then refluxed for 2hours. The solvent was removed in vacuo, ether (50 ml.) was added. followed cautiously by water (30 m1.) and 5 N.hydrochloric acid (20 ml.) The ether layer was washed with water (2 X 20 ml.).and the solvent removed to give crude 2-(2-hydroxyethy1)-3-(6-methoxy-2'- naphthyl)-2-methylcyc1opentanone ethanedithiol ketal (1.80 g., percent). I.r. showed absence of carbonyl frequency and presence of hydroxy bands at 3600 cm".

This dithioketal (1.8 g) was refluxed in acetone (50 ml.) and water ml.) with mercuric chloride (2.0 g.) and cadmium carbonate (2.0 g.) for 20 hours. The acetone solvent was distilled off, the residue suspended in water (50 ml.) and extracted with ether (6 X 50 ml.). The ether was distilled to leave a residue, which was crystallised from benzene (30 ml.) to give 2-(2- hydroxyethyl)-3-(6-methoxy-2'-naphthyl)-2-methylcyclopentanone (0.89 g., 62 percent) m.p. 129- 130C. (Found: C, 76.79; H, 7.48; C H O yam, 76.5; H, 7.42 percent).

EXAMPLE l4 Tetrahydrofuran (75 'ml.) was saturated with acetylene at room temperature for 0.5 hour then, with stirring and bubbling of acetylene through the solution, a molar solution of ethylmagnesium bromide in tetrahydrofuran (75 ml.) was added during 0.5 hour. lcecooling .was then applied and a solution of 3-(6- methoxy-2-naphthyl)-2-methylcyclopentanone-2- acetic acid ,(2 g.) in tetrahydrofuran (25 ml.) was added during 05 hour. Passage of acetylene was maintained at 0C for a further 2 hours, then the mixture was allowed to reach room temperature. Most of the solvent was distilled off in vacuo and the residue was treated cautiously with SN-sulphuric acid (75 ml.). The mixture was extracted with ether (3 X 25 ml.) and the ether extracts were evaporated to dryness. The residue was stirred with 1.5 percent aqueous sodium carbonate (50 ml.) for 3 hours, the resulting sodium salt was filtered off and washed with ethyl acetate (2 X 50 ml.). It was then dissolved in water, acidified with dilute hydrochloric acid and the precipitate which formed was filtered off and recrystallised from ethyl acetate. 1- Ethynyl-3-(6'-methoxy-2-naphthyl)-2- methylcyclopentanol-2-transacetic acid (1.5 g. 70 percent) was obtained as colourless crystals, m.p. 154 156C (Found: C, 74.11; H, 6.66; C H O requires C, 74.15; H, 6.49 percent); i.r. (3 percent solution in CHCl bands at 3470 cm (OH); 3280 cm; (C CH); 1690 cm". (Carbonyl C=O) with a broad absorbance at 3200-2400' (carboxyl OH). N.m.r. bands [in (CD CO] at 8.661 (angular methyl) and 6.921- (C The ethyl acetate used to wash the sodium salt was dried (MgSO and evaporated. The residue was crystallised from ethyl acetate to give l-ethynyl-3-(6 methoxy-2'-naphthyl)-2-methyl-cyclopentanol-Z- acetic acid cis-lactone (0.3 g., percent), m.p. 173 175C, having i.r. (5 percent solution in CHCl bands at 3300 cm (C I CH), 1770 cm. (lactone carbonyl).

EXAMPLE l5 Methyl 3-( 6methoxy-'2 -naphthyl)-2- methylcyclopentanone-Z-acetate (1.25 g.) was dissolved in dry t-butanol (25 ml.) and added to a solution obtained by dissolving potassium (1.0 g.) in dry tbutanol (50 ml.). Amyl nitrite (6 ml.) was added and the mixture was stirred for 2 hours, then the solvent was removed in vacuo at Ether (50 ml.) and N- hydrochloric acid (50 ml.) were added, the ether layer was extracted with N-sodium bicarbonate solution and the sparingly soluble sodium salt was salted out from the aqueous solution with sodium chloride. It was then 8 filtered off, and dissolvedby shaking with ether and dilute hydrochloric acid, the ether solvent was distilled off, and the residue crystallised from 25 percent aqueous methanol to give 3-(6'-methoxy-2'-naphthyl)-5- oximino-2-methylcyclopentanone-Z-acetic acid (0.65g., 54 percent), m.p. 131 133C.

EXAMPLE 16' The acid of Example 15 (0.15 g.), hydroxylamine hy- EXAMPLE 17 Methyl 5-N-methylanilinoformyl-3-(6-methoxy*2'- naphthyl)-2-methylcyclopentanone-2-acetate (0.44 g.) was dissolved in tetrahydrofuran (15 ml.) and concentrated hydrochloric acid (2.5 ml.) and allowed to stand for 1 hour at 20C. The tetrahydrofuran, was removed in vacuo at 20C. The oil was dissolved in ether, washed with water and dried with MgSO The ether solvent was removed to give methyl 5-formyl-3-(6'-methoxy- 2'-naphthyl)-2methylcyclopentanone-Z-acetate (0.28 g., 80 percent) as a gum that would not crystallise from solvents. U.v. (EtOl-l) hmax. 270 ,u (6 10,000) and (NaOH/EtOH) 1 312,11. (e 11,100).

This ester (10.3 g) was dissolved in N. sodium hydroxide ml.), kept for 3 hours at 20C, acidified to give an oil, and the oil was dissolved in ether, washed, dried and the solvent removed to give 5-formyl-3-(6- methoxy-2-naphthyl)-2-methylcyclopentanone-2- acetic acid as an amorphous tan solid (8.63 g., 87 percent). U.V. (EtoH) 11 270 u (e 13,600) and (NaOH- /EtOH) hmax 312 [1. (e 15,800).

Treatment with hydrazine hydrate gave the pyrazole derivative, m.p. 292C (Found: C, 71.3; H, 6.4; N,

. 7.94; C C N O requires C, 71.4; H, 6.0; N, 8.33 percent). 1

What is claimed is:

1. A naphthylcyclopentanone derivative of the formula:

I 2. 3-(6 Methoxy-2-naphthyl)-2-methylcyclopentanone-2-acetic acid or its methyl ester.

3. The compound of claim 1 which is: 

1. A naphthylcyclopentanone derivative of the formula:
 2. 3-(6''-METHOXY-2''-NAPTHTHYL)-2-METHYLCYCLOPETANONE-2ACETIC ACID OR ITS METHYL ESTER.
 3. The compound of claim 1 which is: 